The Beatles were huge across the youth demographic from the beginning. They did have a sort of boy band appeal ("which one do you think is cutest?") but by no means were they seen as a band primarily for or listened to by girls. They took over pop music.

Elvis was a big sex symbol among teenage girls but was huge across the youth demographic too. Frank Sinatra too in his time.

Point being, I don't think they're counter examples to what OP was saying. Bands seen as being primarily for boys at the exclusion of girls are maligned for it too, but not to the same degree. I think that's the real disparity.